Q47634: How to Reboot Your Machine within a Pure C Application

Article: Q47634
Product(s): See article
Version(s): 5.00 5.10
Operating System(s): MS-DOS
Keyword(s): ENDUSER | S_QuickC S_QuickASM | mspl13_c
Last Modified: 16-AUG-1989

Question:

How can I cause my machine to reboot itself from within my pure C
program? Interrupt 19H does not accomplish this task.

Response:

You can do a complete reboot on an 8086-based machine by jumping to
the address F000:FFF0. This action also reboots many 80286 and 80386
machines. The address contains a jump instruction that leads to the
machine's initialization code. For this method to succeed, your
machine must be in real-mode operation.

To prevent a memory check (on IBM and many compatibles), you should
store the value 0x1234 in the memory location at 0040:0072.

The following functions reboot your system without a memory check. If
you wish to allow the memory check to occur, you must remove the
single line comment delimiters, "//", from the lines involving
"memchk".

//int far *memchk ;

void (far *reboot)( void ) = (void far *)0xf000fff0 ;

void main ( void )
{
  // memchk = (int far *)0x00400072 ; /* address of mem. check control */
  // *memchk = 0x1234 ;               /* disable memory check          */

  (*reboot)() ;                       /* reboot your machine           */
}

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